docs: def logout(anchore_config):
      """
      Log out of Anchore service
      """
      ecode = 0
      try:
          aa = contexts['anchore_auth']
          if aa:
              anchore_auth.anchore_auth_invalidate(aa)
              if 'auth_file' in aa:
                  os.remove(aa['auth_file'])
          print "Logout successful."
      except Exception as err:
          anchore_print_err('operation failed')
          ecode = 1
  
      sys.exit(ecode)